1. Field of the Invention
The invention relates to the handling of normally undesirable condensate and is directed more particularly to an assembly and method for disposing of condensate to a drain line or potable water system.
2. Description of the Prior Art
Many processes involve the cooling of air, either for the direct purpose of cooling and/or dehumidifying the air, such as in dehumidification, air conditioning, or refrigeration, or as an indirect result of heating using an air-source heat pump, as, for example, heating water using a heat pump water heater. Depending on the temperature and moisture content of the air, and the degree to which it is cooled, some of the moisture in the air being cooled condenses. The condensate formed must then be disposed of. Normally, this is accomplished using a drain line leading to a drain. Draining condensate can, however, be difficult in many applications. For example, there may be no drain conveniently located to which a condensate drain line can be plumbed, or the drain may be situated such that condensate cannot drain by gravity.
In U.S. patent application Ser. No. 09/059,878, filed Apr. 14, 1998, now U.S. Pat. No. 5,946,927, in the names of John T. Dieckmann et al, and U.S. patent application Ser. No. 09/111,248, filed Jul. 3, 1998, now U.S. Pat. No. 5,906,109 in the names of John T. Dieckmann et al, there are shown and described heat pump water heater and storage tank assemblies in which disposal of condensate is discussed. The aforesaid applications are incorporated herein by reference. As noted therein, one can design an air-cooling apparatus such that condensate is not formed. This is accomplished by limiting the cooling capacity of the cooling apparatus, either by limiting its maximum cooling capacity, or by shutting off, or lowering, its cooling capacity when conditions are conducive to condensate formation. Either alternative usually imposes unacceptable cooling-capacity limits for air conditioning and refrigeration, and eliminates one of the desired functions of air conditioning, i.e., dehumidification. It also restricts the capacity that can be achieved by a heat pump using practical air-flow rates through an air-cooling coil and completely defeats the purpose for dehumidification applications. Alternatively, one can re-evaporate the condensate that forms. This approach, however, imposes several disadvantages, including a) increased cost and complexity of the apparatus, b) reduced reliability of the apparatus associated with increased design complexity, such as the need for float switches and/or other moving parts, and c) increased energy consumption required to evaporate the condensate. For air-conditioning applications, this counteracts the desired dehumidification function of the air conditioner. For dehumidification applications, this completely defeats the purpose.
Where the drain is located at a higher elevation relative to the air-cooling coil, and gravity will not drain condensate, a condensate pump can be used to pump the condensate to the drain. However, a conventional condensate pump and the associated apparatus tend to be costly and are subject to reliability problems due to the use of moving parts such as a float switch, motor, and mechanical pump.
There is thus a need for a condensate disposal device and method for use with air-cooling coils, which device heats and pressurizes the condensate and injects the pressurized condensate to a drain line, potable water system or other water reservoir.
There is further a need for a condensate disposal device and method for use with air-cooling coils, which device does not require a conventional condensate pump.